for (String blockId : msg.blockIds) {
blocks.add(blockManager.getBlockData(msg.appId, msg.execId, blockId));
}
long streamId = streamManager.registerStream(blocks.iterator());
logger.trace("Registered streamId {} with {} buffers", streamId, msg.blockIds.length);
callback.onSuccess(new StreamHandle(streamId, msg.blockIds.length).toByteArray());
} else if (msgObj instanceof RegisterExecutor) {
RegisterExecutor msg = (RegisterExecutor) msgObj;
blockManager.registerExecutor(msg.appId, msg.execId, msg.executorInfo);
callback.onSuccess(new byte[0]);